The present invention relates to a bypass valve system of a turbo-charged engine for bypassing excessively compressed intake air into an air filter wherein excessive compression of the intake air is generated by sudden closing of a throttle valve.
In general, engine output is proportional to engine displacement. However, even engines with the same displacement can have significantly varied output, based on the amount of air supplied to cylinders of the engine. It is well known that the more air supplied to a cylinder, the higher the increase in engine power output. Such technique increasing engine power by controlling the intake air supplied into the engine cylinders is called xe2x80x9csuper-chargingxe2x80x9d.
A turbo-charger is one type of super-charging system that is widely used for increasing the output of an engine by super-charging. Conventional turbo-charge systems include a bypass valve. Conventional bypass valves, however, are disadvantageous in that the opening/closing operation responding to the sudden change of pressures is delayed due to a mechanical operating system. As a result, the compressed intake air reversibly flows into the compressor continuously generating pulsatory noises in the compressor. In addition, the bypass valve generates a squeezing sound when the highly pressurized intake air is suddenly discharged. Further, the intake air violently discharged from the opening vibrates an air filter making a resonant noise.
For the foregoing reason, there is a need for a bypass valve system of a turbo-charging engine that can reduce the noise generated from a compressor, an air filter, and a bypass valve while addressing the drawbacks associated with the prior art.
The present invention provides a bypass valve system that reduces pulsatory noises generated by impact of reversed intake air against a compressor. The bypass valve system bypasses the reversed intake air into an air intake, such as an air filter, before the reversed intake air reaches the compressor.
Furthermore, the present invention provides a bypass valve system that significantly reduces vibrating sound generated by impact of highly compressed intake air against an air filter. This may be achieved according to an embodiment of the invention by opening a bypass valve before the intake air is excessively compressed.
In addition, the present invention provides a bypass valve system that significantly reduces squeezing sounds from the bypass valve. Again, this may be achieved by opening a bypass valve before the intake air is excessively compressed.
Further, the present invention provides a bypass valve system, in which the force of a spring can be readily determined because there are only two factors to be considered in designing the operation of the bypass valve, namely the force of the spring and the pressure downstream of the compressor.
The bypass valve system according to an embodiment of the present invention includes a bypass valve having a diaphragm, which selectively opens and closes a bypass passage in response to a change of pressure downstream of a compressor. A throttle position sensor generates an electric signal in accordance with the degree that a throttle valve is opened. An ECU detects a sudden closure of the throttle valve based on said electrical signal generated from said throttle position sensor and then outputs an activating signal to a solenoid valve. The solenoid valve supplies the pressure downstream of the compressor into the bypass valve in response to the activating signal.
In particular, the bypass valve preferably comprises a main body, a diaphragm, an upper chamber, an operating rod, a spring, a closing element, an inlet and outlet. The upper chamber communicates with downstream of the compressor through a passage having the solenoid valve therein. A proximal end of the operating rod is fixed to the diaphragm, and a distal end is connected to a spring disposed at the lower part of the main body. The closing element is securely fixed to the operating rod. The inlet and outlet are through what the intake air is bypassed. The closing element selectively controls the flow of intake air by moving towards and away from the upper chamber in accordance with the movement of the diaphragm and the operating rod.
For example, when the pressure downstream of the compressor supplied into the upper chamber becomes larger than the force of the spring, the closing element moves away from the upper chamber and opens the bypass passage in accordance with downward movement of the diaphragm. Further, the ECU determines whether the throttle valve is suddenly closed or not, based on a comparison of a predetermined value and a value of time derivative of the electric signal generated by the throttle position valve.
According to another embodiment of the invention there is also provided a method for bypassing excessively compressed intake air in a turbo-charged engine system. A degree of opening of a throttle valve is measured and an electric signal generated that is proportional to the degree of opening. This electric signal is then transmitted to an electronic control unit (ECU). It is then determined whether a throttle valve has been suddenly closed based on the electric signal. Excessively compressed intake air is then bypassed from an intake manifold to a air intake before it reaches a compressor of the turbo-charged engine system. This may be achieved by sending an activating signal to a solenoid valve fluidly coupled between downstream of a compressor and a bypass valve, thereby opening the solenoid valve to allow pressure downstream of the compressor to be supplied to the bypass valve. This opens the bypass valve to allow excessively compressed intake air to be discharged into the air intake.